THURSDAY, Nov. 29, 2018 (HealthDay News) -- It's no surprise that many Americans are working overtime. Conservative estimates say that 19 percent of adults put in 48 hours or more a week and 7 percent log in 60 or more.

But what you might not realize is that, after a certain point, extra hours could be hurting both your health and your productivity.

In addition to a variety of medical issues and unhealthy lifestyle choices associated with long hours, a British study used cognitive tests to show that working 55 hours a week was associated with lower scores in vocabulary and reasoning, and can lead to cognitive problems as you get older.

Adding insult to injury, research done at Stanford University found that, besides the personal toll that overtime takes, you probably aren't working effectively. Productivity starts to fall considerably after the 50th work hour of the week and gets worse with every additional hour. So, if you put in 70 hours a week, you're not likely to accomplish anything worthwhile during those last 15.

One reason for this is that you might be too stressed or tired to function at peak level since working overtime usually results in your getting less sleep -- and that in turn leads to making mistakes that can set you back at work.

Take action to improve the balance between your personal life and your work life. Prioritize responsibilities and focus on the most important ones. Assert more control over time-draining tasks like answering emails. If you check your email every few minutes, cut down to every half hour or just scan the subject lines and open the most essential ones.

And when you must stay late, make getting sleep a priority so that you'll be well rested when you're back at work in the morning.